Standard Erection Manual (Supporting Structure)

STANDARD ERECTION MANUAL (Supporting Structure)

Prepared by Power Sector – Technical Services (HQ) Noida

Corporate Quality Assurance Bharat Heavy Electricals Limited, New Delhi 1

INDEX S.NO 1.

TOPIC

Instruction No

A) Introduction

B1 – 01-0101G

B) Erection Sequence 2.

Foundation Checks

B1-01-0102T

3.

A)

Pre- Assembly Column & Bracings

B1-01-0103T

B)

Preparation for Erection of Columns without pre- assembly

C)

Erection of column & bracings

D)

Welding & NDE

A)

Pre- Assembly Girders

a)

Web Horizontal, Welding & NDE

b)

Web Vertical, Welding & NDE

B)

Erection of Girders

4.

B1-01-0104T

5.

Preparation for drum erection

B1-01-0105T

6.

Post Drum Erection Checks and works

B1-01-0106T

7.

Platform Stairways & Galleries Erection

B1-01-0107T

8.

Structural Steel Erection Notes

B1-01-0108T

9.

Annexure i)

Man Power

II)

Bar Chart

B1-01-0109G

IIIa) Erection Tolerance

B1-01-0109T

2

A)

Introduction Boiler supporting structure forms 25% of the total weight of a steam generator. The entire pressure parts are suspended from the structural steel work. In addition to the above air pre-heater (tubular and regenerative) load, partial load of ducting and piping are included. Also it forms platforms at various levels for the movement of operator and space for maintenance of various equipments. Hence structural safety and stability are the ultimate objectives of the design. The prime aim of an erector is to meet the design requirements with optimum utilization of men, material and time. To achieve the above, the erector shall adopt all technological improvements that have taken place in the area of structural steel erection. The sequence of structural mainly depends on the availability of major handling equipments like Tower crane, Crawler crane, derrick etc. This section describes mainly on boiler supporting structural erection up to drum lifting. However erection activity of supporting structure for air heater, ducts, piping, etc., Continues, on similar lines, till completion.

B. Erection sequence with the availability of Major T&P a)

Tower Crane It has capacity to lift components including ceiling girder. Piece by piece erection shall be followed for all main, auxiliary and middle columns.

b)

Crawler Crane It has capacity to lift structural components including ceiling girder. i)

Piece by piece erection of column shall be followed for main and auxiliary columns.

ii)

Erection of column S12and S4R can be deferred till crane is brought out of furnace area. Rest all columns with bracings are to be erected.

iii)

All Columns in Air Pre heater area are also to be erected.

iv)

Erect Ceiling girders G1L, G2L, G3, G2R and other Welded and rolled beams.

v)

Erect Column S12 R and Bracings.

vi)

Erect Girder GIR.

vii)

Erect Column S4 R lastly

3

C)

Derrick with Crawler Crane

i)

Piece by piece erection of columns shall be followed for main and auxiliary columns up to 4th piece (approx 33M) using crawler crane. Crawler Crane, with Jib to be used for 4 th piece erection.(Jib Cap. # 130/150)

ii)

Final piece is to be erected with derrick.

iii)

Along with the sequence of erection of ceiling girders the middle row columns (S14, S15) including the one which deferred (S13 orS18) are to be erected with the help of derrick or crawler cranes.

d)

Follow Manufactures instructions strictly while lifting loads as under: i)

Crawler Crane: - Lifting load with respect to boom angle shall be monitored. - Positioning and the movement of crane shall be only on the consolidated and leveled ground. - Boom swing speed with load shall be monitored.

ii)

iii)

Tower Crane‟ -

Lifting load with respect to radius of lifting shall be monitored.

-

Boom swing speed with load shall be monitored.

Derrick The maximum inclination of derrick permitted to lift load is 4 o with proper tightness of all guy ropes and bottom locking.

C.

Measuring Instruments The following measuring and test equipments calibration to be ensured and made available prior to start of structural erection. Tape 5M

4 Nos

30M

2 Nos

Torque Wrench

650-1000 ft Lbs

Dumpy level Bolt tension calibrator. Temperature recorder (range 0 to 300Oc)

4

Theodolite In addition to the above piano wire without knots and kink~ plumb bob with oil dash pot and thermal chalks to be made available. FOUNDATION CHECKS i)

Permanent bench mark to be obtained from civil group.

ii)

Reference axes (Boiler longitudinal and transverse axes) to be obtained from civil group.

iii)

Orientation of Foundation -

Foundation bolt location

-

Shear lug opening

iv)

Typical arrangement of foundation pedestal. (Refer Fig .1A)

v)

Check the following -

Top level of each foundation with reference to bench mark.

-

Mark the axes of each pedestal.

-

Disposition of pedestal with respect to reference axes (Boiler and transverse axis)

-

Spacing between adjacent pedestal

-

Diagonals distance between pedestals.

-

Foundation bolt disposition with respect to pedestal axes and diagonals.

-

Dimensions of shear lug opening (length, width and depth).

vi)

Chip the pedestal top surface to remove loose layer.

vii)

Clean the foundation top surface, bolt pockets and shear lug opening.

viii)

Foundation bolt vertically and correctness of threads.

ix)

Check the freeness of nut over foundation bolt threads. Bolt thread ends to be protected till final fit up.

x)

Decide the thickness of packet say “t” mm -

Length measured from “0” Meter) elevation marketing to bottom of) base plate)

5

-“A” mm

-

Elevation of top pf pedestal - “B” mm thickness of packer required = (-B) – (-A) = - „t‟ mm

-

If „t‟ is less than 35 mm top pf pedestal to be chipped off to achieve minimum grouting gap of 35 mm.

-

If “t” is more than 75 mm the same may be informed to manufacturing unit for acceptance.

-

The thickness of packers shall be selected in such a way to use maximum of only 5 nos. If shims are used the same shall be placed between the packers.

6

7

E)

Position of Packers (Refer Fig. 2)

i.

Packers are free from undulation.

ii.

Packers are to be located below the columns flange line and parallel to the flanges. Wherever shear lugs are interfering, the packers are to be cut suitably.

iii.

Chip the pedestal surface at packer location for proper seating of packer. Or The first packer can be aligned over the rough concrete (without chipping for level) using high strength quick cement. Allow the mix to cure as per the manufacturer‟s recommendation.

iv.

Further packers/ shims are to be provided over the aligned forst packers to achieve the calculated thickness of packers. Notes: The total height of packers shall be plus 3 mm than the calculated thickness to accommodate setting of packers during loading.

v.

Level both sets of packers top in one plane.

8

Fig. 2

9

a) i)

Pre Assembly of Column:

Preparation of pr assembly bed is very much essential for preassembly of columns. Keeping the piece in „H‟ position. The pre assembly bed shall be arranged in such a manner that each column piece should have minimum three bottom supports (one at the middle and other two one meter away inside from the column ends) to avoid excess sagging or over handing of pieces at ends. The bed shall be prepared over a consolidated and hard ground to avoid any possible sinking of bottom supports during loading with column pieces. The span between the supports to be decided based on the individual piece length. The width of the bed shall be minimum 6 Meter so that three or four individual column pieces can be preassembled at a time with the help of gantry crane. The bed preparation should suit the pre assembly of ceiling girders and pressure parts also. The suggested pre assembly bed arrangement is indicated in Fig. 1B. Note: Top level of all support beams shall be maintained with in ± 3 mm using water level. Minor adjustments are to be made using shims to accommodate the section variation of individual column pieces.

ii)

Identify the individual column pieces Work order no PGMA DU No. Column designation These details are stenciled and punched on each piece Figures 2A, 2B, 2C, 2D indicate the identification details.

iii)

Position all pieces on the pre assembly bed.

Note: 1) 

No inter changing of column pieces and Rotation 180 o degree is permitted.



The match marks given by the sop shall be strictly followed. Fig .3 indicates the shop match – mark details.

10

2) iv)

Do not sling structural members without application of protective materials like flexible thick non metallic piece.

Check and measure the following in the individual pieces. Ensure they are within the limits. Otherwise…………

Fig. 3

11

Fig. 4

12

Fig. 5

13

Fig. 6

14

….. refer to manufacturing unit for repair procedure / Comments. (Ref, to Annexure – 3B). Camber Sweep Twist Ensure no damage to milled ends, if any Ensure cleanliness of cover plate area 1n the flange and web in the column joint area and HSFG Bolt area. Ensure deburring of bolt holes, if required. v)

Align all the pieces by pulling each piece to have proper contact at milled end and tighten with service bolts in the rest plate provided on the flanges of the column Pieces.

vi)

Align for web to web, flange to flange match marks.

viii)

Check the following: 

Camber and sweep for the full length of assembly (the permissible limit is 1mm/ M Max 18 mm).



Milled end adjustment of each joint by using feeler gage Localized gap of 0.5 mm is permissible.

ix)

Position the cover plate with shims (for change is sections) supplied with web Supplied with web and flange. No interchanging of cover plate is permitted. (Shop match marks are to be followed).

x)

The service bolts (HSFG, Bolts shall not be used) for positioning the cover plate.

xi)

Ensure the heating of joints fro welding of cover plate.

xii)



Gas heating (neutral flame can be adopted for thinner sections (up to 40 mm)



Electrical coil heating for section thickness above 40 mm to get uniform heating in welding area.

Prior to welding ensure the contact area between flange and flange cover plate to achieve the same “L” Clamp with wedges is to be used.

15

Fig. 7

16

xiii)

On random samples carry out LPI/MPI on weld to ensure the soundness of the weld. (Ref. Fig.5A & 5B).

xiv)

Punch mark the elevation at every 5 meter from top. (Say 57.xxx, 55, 50 … 5, 1 and 0). See Fig: 6.

xv)

Accordingly punch mark the 1 M and 0 M elevation over the bottom piece.

xvi)

Measure and record the distance from „O‟ Meter to bottom of the base plate. Based on this the packer thickness for individual column is decided.

xvii)

Cleat angles to be welded at the appropriate level for the placement of horizontal on flange and web side.

xviii)

Fix the vertically stickers over individual column pieces on web and flange in two places (near MBL Locations). -

For bottom piece at 1 „M‟ elevation and below the both joint area at the convenient level.

-

For other pieces near ends (just near bolt area) at the convenient level.

Note: The center line of stickers shall be matched with center line marking of web and flange (shop punched) Refer Fig:7. xix)

Dismantle the column pieces from the pre assembly bed and stack it near the erection area. To suit the sequence of erection, piece by piece, from bottom to top. - Preserve the milled end portion. - Paint the welded area after NDE checks.

b)

Preparation fro erection of column‟s without pre-assembly:

i)

All the column pieces are to be identified with work order no., PGMA, DU no. and column – designation which are stenciled and punched on each piece.

ii)

Total length of the top four pieces of a column is to be calculated to arrive at the length of bottom piece as per drawing up to „0‟ Meter elevation.

iii)

Punch mark the „0‟ Meter and „1‟ meter elevation over the bottom piece.

iv)

Check the distance from „0‟ Meter elevation to bottom of the base plate to calculate the packer thickness.

17

v)

The variation, if any in shop punched overall length variation (O LV and site measured O LV to be informed to manufacturing unit for comments.

Fig. 8

18

Fig. 9

19

vi)

Check individual column piece camber, sweep, twist and milled end condition, Inform manufacturing unit on deviations for correction / comments.

viii)

Clean the HSFG bolt area in the column pieces and cover plate area. The cover plates moved from column pieces are to be identified and kept separately for re-fixing at the correct location during erection.

viii)

Punch mark the elevation at every 5 Meter from top.

ix)

Fix the cleat angle at the appropriate location on the flange and web portion of the column pieces for placing the horizontal members.

x)

Fix vertically stickers on the web and flange as explained in preassembly of columns.

c)

Erection of columns & Bracings:

iii)

i)

Lift the first column bottom piece as shown in the Figure: 8.

ii)

Place the column piece over the foundation with out damaging the Bolt threads, while lowering the piece through bolts. Tighten the bolts prior to releasing the load from crane.

iii)

Erect all the first piece of the columns in this manner

Align the individual pieces (verticality etc.) for the following (Ref. Fig.9) 

Elevation (1 meter punch mark shall be taken as reference for all column pieces)



Spacing between adjacent columns with respect to reference axis of boiler.

v)

Tighten the foundation nut and recheck the alignment, alignment procedure to be repeated, in case of ant disturbance.

vi)

Check the spacing columns at horizontal beam level.

vii)

Check the length of the horizontal member and compare with the measurement of space between columns (Any minor correction on horizontal member to be some at ground level).

viii)

Box up the column as follows 

Box I S9-S10 – S1 –S2 (Left and Right. Fig IOA)

Connect with horizontal members and complete cleat welding (Figure 11- A & B). Note: Do not sling structural members without application of protective material like flexible thick non- metallic piece.

20

Fig. 10

21

Fig. 11

22



Box II S11 – S12 – S3 – S4 (Left & Right . Fig: 10B)

Connect with horizontal members and complete the cleat welding (Figure: 11 – A & B). ix)

Measure the distance between Box I to Box II and Box III on both sides and tally with horizontal member length measured at site (necessary correction on horizontal member to be carried at ground level (Figure 10 D).

x)

Erect the horizontal members between the aligned boxes (Fig: 11 – A & B).

xi)

Complete the welding of cleat angle with horizontal member and column (between boxes).

xii)

Erect and along the vertical bracings.

xiii)

Position, align and weld the gusset plate at its location.

xiv)

Position, align and weld/ bolt the vertical bracing with gesset plate (Refer Fig: 12 – A to E)

xv)

Erect the front middle and rear middle column pieces and align as explained for other pieces.

xvi)

Erect and align the horizontal members and vertical bracings and complete the welding.

xvii)

Complete the erection alignment and welding of Main brace level (MBL) members in the boxes ups section.

xviii)

Check the vertically of all columns and compare with previous readings.

xix)

Complete the grouting up to the bottom of the base plat and cure. (Ref.Annexure - 4).

xx)

Prepare the protocol for the completion of first piece erection and obtain clearance for second piece erection.

xxi)

The above mentioned steps are to be followed for subsequent piece erection (Ref. Fig: 12) - After the erection of second and subsequent piece the flange cleat bolts (at 4 locations) are to be tightened uniformly. - Provide web cover plate on either side following the shop match marks.

23

- Fix the required length HSFC bolts with washer on nut side and snug tighten the web cover plate (Refer Annexure 5).

Fig. 12

24

Fig. 13

25

Fig. 14

26

Fig. 15

27

Fig. 16

28

Fig. 17

29

Fig. 18

30

Fig. 19

31

Fix the required length HSFG bolts with washers on nut side and snug tighten the flange cover plate. (Refer: Annexure – 5). If the bolt length at a particular joint is more (shank length) hardened washers upto 3 Nos. (max 4 Nos) have to be used and placed suitably. Note: Snug tightening mean tightening of fasteners by one person using correct size of ring spanner without any leverage. The sequence of tightening is always from fixed part of the connection to free edges and inner row; to outer row. (Refer Fig: 14A). Note: Flange cover plate fixing for columns erected without Pre-assembly. a)

If the pre assembly of flange cover plate is not done follow the sequence for fixing the flange cover plate for all column joint with HSFG bolts and welding‟ as shown In Figure 14B.

b)

Provide the flange cover plate complete (with shims wherever required).

c)

Preheat and weld the flange cover plate to the column, after ensuring proper contact. If mentioned in the drawing.

d)

Fix the HSFG bolts with washer and snug tighten them.

e)

Erection, alignment and welding sequence explained for first piece shall be followed for second and subsequent piece erection.

xxii)

HSFG bolts in flange and web areas are to be tightened only by TURN OF NUT METHOD following the sequence explained for snug tightening. Cross check the tightened bolts using calibrated Torque wrench. (Set the torque wrench to required value using bolt tension calibrator) (Ref.Annexure -5).

Note: a)

The vertical bracings at the top levels may be deferred till the erection and alignment of first and last ceiling girder for easy adjustment. Rest of the columns erect the vertical bracings and do final welding.

b)

Vertically of columns is to be checked before the erection of ceiling girder.

c)

Prior to erection of top piece, the girder pin connection matching and welding of support plate with column top shall be completed as explained below:

32

The girder pin connection assembly is applicable for S11 & S13 columns (both right & left) and S18, S19 and on beams connecting S11L – S18 – S11R and S13KL- S19-S13R. (Refer Drawing: Pin connection key plan. Align the axes girder pin bottom part and column top.

33

Fig. 20

34

Typical girder pin connection details are shown in the Fig: 15 A to be obtained from Trichy. 

Check the contact better bottom part pf girder pln with flange web and stiffener portion of column top using feeler gauge. Full contact is to be ensured.



Assemble the holding down plate with fasteners and align with column top and pin assembly bottom part on either side of the flange.



Tack- weld the holding down plate with column and bottom part of pin connection. Provide stiffener to avoid welding distortion.



Dismantle the assembly.



Preheat and Complete the welding.



Flush grind the weld in the matching surface.



Alternately the connecting plates can be welded at site at 5 mm away from column top and end and pin and as shown In Fig 15B. Any distortion of connecting plate during welding and any extra projection of welding will not affect the required full contact of pin.

LATERAL STABILITY OF COLUMN WITH HORIZONTAL & VERTICAL BRACINGS (REF. FIG: 16). i)

Vertical bracing gives lateral stability to column offering resistance to horizontal forces coming on the structure & transferring the forces to column base / foundation safely.

ii)

To maintain column stability In both X, Y direction against lateral buckling, lateral supports are to be given.

iii)

Lateral support is given by the net work of horizontal bracings at about 8 to 10M height.

iv)

Horizontal bracing gives resistance to lateral buckling of columns due to wind / seismic / stability force.

v)

The horizontal force through the horizontal bracing system is transferred to vertical bracing nodal points and from there to the ground without causing undue sway to column.

vi)

Discontinuity in horizontal bracing will result in ineffectiveness & will not give resistance to the sway of column effectively.

vii)

To transfer the lateral forces effectively to ground continuity of vertical / diagonal bracing from ceiling to column base is very much essential.

35

Fig. 21

36

Fig. 22

37

d) Welding and NDE Requirements: 1.0 Welding a) Welders shall be qualified as per AWS D 1.1(Latest) or AS ME Section IX. b) Welding consumables conforming to the design requirements shall be used. c) Selection of welding consumable shall be out of the “Approved list of welding consumables” indicated in the Welding Manual Vol.1 (Chapter IV) d) Only basic coated electrodes are to be used as mentioned in drawing. Manufacturer‟s batch certificates are also to be verified. e) Welding consumables used for this are to be stored properly and issued after necessary baking as detailed in welding manual Volume I. Electrodes issued for job should be kept in holding ovens and maintain the temperature. f) Pre-heating requirements for materials shall be strictly followed as mentioned. g) Welding shall not be done when the surfaces are wet, oil traces are seen or exposed to rain or high wind or when the welders are exposed to inclement conditions. h) The sizes and length of weld shall not be less or substantially in excess than the specified in the drawing. 2.0

Preheating and PWHT For structural members refer Field Heat Treatment Schedule (HT – Com) Table IV (Structural).

3.0

NDE Requirements a)

For structural members the following can be followed: i)

Butt joints



100% MPI / LPI for back gouged/ chipped area before welding.



t > 32 mm 100 RT.



t > = 25 mm < 32 mm – 100% MPI on finished weld.

38



t < 25 mm MPI / LPI on finished welds limited to 10% of weld length at random.

ii) 

Groove joints In case of double side groove joint 100% MPI/LPI for back gouged / chipped area before welding.



t > 25 mm 100% MPI on finished welds.



t = < 25 mm MPI / LPI on finished welds limited to 10% of weld length at random.

A)

Preassembly of ceiling girder: 

Identify the pieces for the following 

Work order no.



PGMA



DU NO.



Girder designation.



Position the girder pieces over the pre-assembly bed (made for the columns) keeping left, middle and right side pieces following shop punch mark details.



Check and measure the following



Camber Length & Diagonal



Sweep



Twist (Ref. annexure – 3B)



Edge preparation and condition



Web height at extended portion and compare with flange to flange inner distance (For easy insertion 1 mm gap to be ensured on either side. If required grind web ends to achieve the above).



Major deviation of any, to be informed to manufacturing unit for corrective action. Rectify the deviations accordingly.

39

a)

Preassembly keeping WEB Horizontal: 1.0 Pre –assembly i)

Align the pieces over pre- assembly bed as indicated in Figure 17A. Numbers indicated in circle are the near side of the flange and other numbers are for farther side of the flange.

Note:

ii)

Keep anyone location as datum and measure horizontality (using water level) of the assembly. Shims can be added between girder flange and bottom support to achieved horizontality within 5MM.

iii)

The alignment shall be done in such a way to achieve total length of girder (End connection center to center) after welding including weld shrink at joints.

iv)

Check the following for the total assembly 

Camber



Sweep



Overall length between end connection centre



Web flatness using piano wire



Flange vertically Using plumb bob.



Diagonal of the assembly



Weld fir up at the flange and web joint use „L‟ clamp (Ref. Fig: 17B).

1) Refer fit-up‟ for girder preassembly with we vertical and Annexure 3B for more details on Dimensional deviations permitted. 2) Web root gap shall be more by +2 mm over the flange root to take care of weld shrinkage in flange welding. If needed the web ends to be ground suitably. v) Provide stoppers on flange side as indicated in Figure 17C to take care of the free movement of girder assembly along its length during welding. vi) Support the overhang portion of web to avoid disturbance at web joint.

40

2.0 Preheating i)

Preheating to be carried using electrical resistance method to achieve uniform heating throughout the weld region. Pre heating shall be 150oC.

3.0 Welding a)

The sequence of welding to be followed as indicated in Figure 17D. (Welders engaged for ceiling girders welding are to be qualified as per AWS D 1.1 or ASME See IX).

b)

Complete the root plus three runs on inner side as per the sequence shown in Figure 17D.

c)

Back gouge / chip the weld from outer side and carry out LPI/MPI for ensuring defect free root weld.

d)

Complete the outer side welds for three runs as per the sequence indicated in Figure 17D.

e)

Complete the flange joint weld, around 60% thickness of the joint on both sides of flange alternately (inner and outer) as per the sequence shown in Fig: 17D.

f)

After completion of 60% of flange welding check the web alignment (adjust with wedges to achieve web alignment if required).

g)

Check the root gap. If required, ground to get the gap,

h)

Preheat to 150oC and adopt the weld sequence for the web root. Welding plus two runs as shown in the Figure: 17D.

41

42

Fig. 23

43



Back gouge/ ship the second side of the weld to achieve defect free root: weld.



Carryout LPI/ MPI on the weld joint on root side



Complete the two runs of weld on the second side as per the sequence shown in Fig: 17E,



Complete the balance flange joint and then the balance web joint as per the sequence indicated respectively in Fig: 17D & 17E.

Note: The welding sequence of flange and web can be changed depending on the number of welders engaged.

4.0



Complete the fillet welding between flange and web on both sides.



Carry out the post heating of weld joint for 1 hour at 250Oc.

Post weld heat treatment (PWHT Also refer point 7.0 in page 14 of this section) 

For effective weld thickness > 50 mm PWHT shall be carried out for carbon steel material.



In case of high tensile steel effective thickness 50mm and above PWHT shall be carried out.

Note: For preheating, post heating and PWHT the temperature range given in Erection weld sequence (EWS) to be referred. 5.0 NDE: Carry out the following NDE checks (Also refer point no. 8.0 in page 16 of this section) -

100% RT for flange joints.

-

100% RT for web joints

-

100% MPI for filler joint

Note: Fix and Weld the loose stiffener plates coming near the Girder preassembly joints, before doing the post weld Heat treatment. 6.0 Final Check- and finishing i)

Repeat the dimensional check (carried out prior to welding) after PWHT and Compare the same.

44

ii)

Clean and paint the weld region.

iii)

Check the holes drilled in the web of ceiling girder (distance from the end and C/L distance of each group of holes which is the C/L distance of W.B‟s ).

Fig. 24

45

iv)

Check the size and location of pad plates welded on the web of ceiling girder. These pad plates are to be welded only on sides and bottom face.

b)

Pre assembly keeping Web Vertical: 1.0 Pre assembly: a)

Identify the pieces as per work order No. PGMA, DU and Girder No.

b)

Check the individual girder pieces with respect to drawing.

c)

Check the length, camber and sweep of individual pieces.

d)

Check the web height (between flanges‟ Inner sides) at field joint.

e)

Check the condition of edge preparation at the field joint and carry out correction, if necessary.

f)

Ensure pre-assembly bed is made on the leveled and consolidated area to avoid sinking during placement of girders on the bed.

g)

Ensure the pre-assembly bed members are properly spaced to avoid sagging of girder pieces when they are placed over. (Refer Fig.: 18)

h)

Match the pieces as per match marks provided in the pieces. Ensure the orientation of girder pieces as per drawing (Ref. Figure 19).

2.0 Fit Up a)

While leveling the pieces, the reference lines punched on the web at about 1 to 1.5 M level from bottom flange may be taken as reference.

b)

While adjusting the over all length of girder, check the distance between girder pin connection bolt hole centers which is marked in the bottom flange as well as top flange.

c)

While adjusting the over all straightness of the girder piece the longitudinal centre line of the girders and web line marked on the pieces may be taken as reference.

d)

While matching the piece, flange root gap and web root gap shall be maintained between 4 to 6 mm and 6 to 10 mm respectively in the field joint areas. The reference lines punched

46

on the flange and web on the either side of the joint may be taken as reference (Ref.Figure: 20). e)

The parts to be joined by fillet welds shall be brought as close as practicable. The gap between the parts shall not exceed 4.8 mm. If the separation is 1.6 mm and more than leg of the fillet shall be increased by an amount of separation.

f)

Abutting parts to be joined by butt welds shall be carefully aligned. An offset exceeding 10% of the thickness of the thinner part, but in no case more than 3.2 mm may be permitted.

g)

Dimensional tolerance of the cross sections of groove welded joint with root gouged shall not vary more than the following: i)

Root face of joint

Not limited

ii)

Root opening of the joint: + 1.5 mm – 2mm

iii)

Groove angle of joint:

+ 10o, -5o

Root opening wider than that permitted as above may be corrected by welding with proper preheating and with NDE check (i.e. MPI / LPI) to ensure the soundness of build ups. h)

Members to be welded shall be properly aligned and held in position by bolts, clamps, wedges and other suitable devices until welding is completed.

Fig. 25

47

i)

No tack weld to be made in the web for aligning. Instead „L‟ clamps and wedges shall be used for web alignment to keep the joint free during the welding of flange joint.

j)

Tack welds are not permitted in the end or corner Areas.

j)

Ensure after dimensional check the girder assembly is properly locked in position by using stoppers, “L” Clamps, wedges, guy ropes and struts or by any suitable device to avoid distortion during welding and PWHT operations. * Ensure proper locking, in such a way that the girder assembly can move longitudinally during welding and PWHT operations to avoid accumulation of thermal stress.

3.0

Dimensional check-up a)

b)

Section depth and flange width can be checked as cross reference, since these are already checked up in shop. 

Section depth up to 1 M :

+/ - 3 mm



Above 1M

:

+/ - 4.5 mm



Up – to 2 M

:

+ 7.5 mm



Above 2 M

:

- 4.5 mm



Flange width

:

+ / - 3mm

Check the following dimensions prior to clearing the assembly for welding and are to be recorded in the log sheet 1. Level of the girder assembly. 2. Deviation In straightness on both flanges. 3. Flatness of web on both vertical and horizontal axis. 4. Out –of – square ness of the assembly. 5. Flange and web joint alignment. 6. Overall length of the assembly / Girder pin bolt hole to hole distance 7. Flatness of bottom flange in girder pin locations. 8. Longitudinal and cross diagonals of the assembly.

48

9. Welded beam location distance on either side of the field joint. 4.0

Dimensional tolerance 1. Individual piece camber and sweep

:

max.5mm

2. Individual piece length

:

± 5 mm

3. Level of girder assembly

:

Max 5 mm

4. Deviation in straightness on total

:

Max 15 mm

5. Flatness of Web

:

Max 10 mm

6. Out – of – squareness of assembly

:

Max 8 mm

7. Overall length of assembly

:

± 15 mm

(With the recommended gap for welding of web and flange at field joints, the overall length of the girder shall be achieved within limits after allowing weld shrinkage). 8. Flatness of bottom flange at girder pin connection location

Max 2 mm

9. Longitudinal and cross diagonal of assembly (difference)

Max 15 mm

5.0 Pre-heating i) Flame cutting Thickness 50 mm and less

Nil

Thickness 50 mm and above

100Oc

ii) Welding a) Pre –heat temperature required for various range of plate material thickness is as follows: 

T

UP TO 19 mm

:

Nil



T

Over 19 mm UP TO 38 mm

:

65OC



T

Over 38 MM UP TO 63 mm

:

100oC



T

Over 63 MM UP TO 19 mm

:

150Oc

b) It is desirable to pre-heat using electric resistance coil heaters. Use of self preheat is not permitted.

49

c) When electrode of 3 mm and below are used the minimum pre-heat temperature shall be increased by 50Oc from the pre-heat temperature mentioned above. 6.0 Welding a)

Welders shall be qualified as per AWS D 1.1 (latest) or ASME Sec IX.

b)

Welding consumables conforming to the design requirements shall be used.

c)

Selection of welding consumable shall be out of the “Approved list of welding consumables” indicated in the Welding Manual Vol.I.

50

Fig. 26

51

Fig. 27

52

a)

Butt welds in plates over 50 mm thick shall be PWHT for unequal thickness of plates, the groove depth at the Weld shall be considered for PWHT.

b)

The fillet welds for fixing attachments like pads etc, made on tension flanges over 50 mm thick shall also be post weld- heat treated. 

For high tensile steels (DIN 17100 ST 52.3, IS 961-HTW)

a) Butt welds in plates 50 mm and above thick shall be PWHT. For unequal thickness of plates, the groove depth at the weld shall be considered for PWHT. b) The fillet welds for fixing attachments like pads etc, made on tension flanges 50 mm and above thickness shall also be post weld heat treated. For the fillet welds joining the tension flange to web need not carry out post weld heat treatment. All the post weld heat treatment Cycle shall be 600Oc to 650 Oc . The above cycle shall be controlled within a tolerance of + / 10Oc. The recommended temperature for PWHT must be selected as the mid point of the recommended range. Soaking time: for PWHT shall be “1 hr. / 25 mm thick” up to 50 mm and 2 hr + 15 minutes for each additional 25mm Thickness over 50 mm. The heating rate above 400Oc and cooling rate after PWHT up to 400oC shall be as follows: Thickness Range

Rate of Heating

Rate of Cooling

Up to 25 mm thick

220oC/hr

110Oc / hr

Over 25 -50 mm thick

110Oc / hr

110Oc / hr

Over 50 -75 mm thick

75oc / hr

110oc / hr

Over 75 mm thick

55Oc / hr

65Oc / hr

Autographic Calibrated recorded shall be used to record rate pf heating, soaking and rate of Cooling.

53

Fixing and location of thermocouple shall be made as per details In Welding Manual Volume I (Chapter IV sheet 7/30). 8.0

N.D.E Common requirements for ceiling girder assembled keeping web horizontal / vertical. Cut edges a)

Flame cut welding edges for thickness over 30 mm.# 100% MPI.

b)

For all edges of thickness above 20 mm. # Random MPI 

Weld build up areas -





Weld build up areas in flanges and web – 100% MPI / LPI

Flange butt joint -

100% MPI for thickness 25 mm and above.

-

100% RT for thickness 32 mm and above.

Web butt joint a) 100% LPI for back gouged / chipped area before second side welding. b) SPOT RT – 100%. The defective areas shall be further repaired and re-radio graphed.



Fillet Welds a) Fillet weld between (tension) bottom flange and web 100% MPI. b) When both flange and web are above 25 mm – 100% MPI. c) Other fillet welds – random MPI.

9.0 Final check up and finishing 

After PWHT, surface to be cleaned properly and painted with two coats of red oxide primer.



Cement washed surfaces are to be cleaned properly in the HSFG bolt area including cleat angles.



Dimensional check – up of girder shall be carried out and to be recorded in the log sheets.

54



“No stray arc” shall be done on heat treated members.

B)

Erection of Ceiling Girders

1)

On completion of ceiling girder pre-assembly girder pin connection to be matched at bottom of ceiling girder.

2)

The reference axes used for pin connection assembly with column top to be matched with ceiling girder bottom bolt hole axis.

3)

Check the contact between pin connection assembly top part with ceiling girder bottom flange.

4)

Fix the holding down plate on either side of p1.n assembly and fasten the same with ceiling girder.

5)

Check the alignment an tack weld the holding down plate with pin connection top part. Provide stiffener to avoid welding distortion.

6)

Dismantle the assembly.

7)

Pre heat and complete the welding.

8)

Flush grind the weld on matching surface. 

10)

Alternately the connecting plates can be welded at site at 5 mm away on either side of pin assembly. Any distortion during welding or any extra projection of welding will ot affect the required full contact of pin.

Dismantle the pin connection and carry out the following. - Clean the pin surface and matching surface of top and bottom part. - Inspect the pin rod for any visual defects and carryout LPI test. - Reassemble the pin connection applying molibedenum disulphate (Anti seize compound) or bonium disulphide and weld the clip as per drg:- Tack weld the clip with top part of the pin assembly to avoid tilting while erection. The tack weld to be removed only after the alignment of ceiling girder to make the pin connection effective.

10.

The lifting lug provided, over the individual ceiling girder piece are not meant for lifting total assembly. The suggested lifting arrangement is given in Fig. 23.

11.

a)

Assembled ceiling girder shall be positioned near the boiler in correct orientation.

55

b)

Centre line of ceiling girder is punched on either side of top flange. This will enable to know the difference between boiler axis and C/L of ceiling girder after erection.

c)

Temporary ladders are to be fixed on both the ends and temporary hand rails on top flange of girder.

12.

Assemble the girder pin connection with respective ceiling girder bottom.

13.

Lift the girder and position over column either from front end of from rear and to suit the site condition and major T & P used for erection. Ref: Fig. 24 A for combustor ceiling structure key plan & fig. 24 B for back pass ceiling structure key plan

14.

•

Place

WB F4 over SPR – S17, WB F3 over S17 – S9L WB E4over S9R – S10R, WB E3 over S9L – S10L WB G over S10R – S10L WB F2 over S11R – S18, WB F1 over S18 – S11L

15.



Align the axis WB, bolt hole, with left, right and middle column S11R – S18 – S11L bolt holes. Align pin bottom part and column top.



Use the correct size bolt and tighten the same.



Erect balance welded beams and complete other ceiling structure members WB A R & L, WB B 1 & WB B2, WB C2& WB C1 – in Combustor Area.

In back pass ceiling structure area at 66.100 M elev. * Erect Ceiling Girder G1 R over S11R – S13R & * Erect Ceiling Girder G1 over S11L- S13L * Erect Ceiling Girder G3 over S18 & S19 * Erect Ceiling Girder G 2L & G 2 R after erection of box 400 and beams on S S11 – S18 – S11R & S 13 L – S19- S 13 R 

Align holding down bolts holes with column top and fasten the same. Long stud bolts shall fasten with ceiling girder and column top or furnace side.



Note: Provide stay rope till the ceiling girders are boxed up with WBs for safety reasons.

56

16.

When two adjacent ceiling end RB‟s are positioned, tack weld the cleat angle. Note: In welded beams, pad plates are welded for facilitating the erection of rolled beams over it. Hence before lifting the WB‟s ground with respect to WB drawings.

17.

Follow the same for subsequent erection of ceiling girder.

18.

Align all ceiling girder and check for the following: (Refer Fig: 24 B).

19.



Spacing between the girders – S.



Diagonals between the girders – D

On completion of ceiling girder alignment carryout the following. - Complete the welding of cleat angle with WB‟s - Complete the tightening of HSFG bolts. (Only by turn of nut method and counter checked with calibrated torque wrench). - The left out stiffener plates are to be welded with ceiling girder.

20.

Erect, align and weld all ceiling bracing members and compression members between ceiling girder top. Note: The members in the drum lifting region may be deferred till the completion of drum lifting and the same shall be erected immediately after the drum lifting operation.

21.

Check the vertically of all columns after the alignment fo ceiling girders.

22.

Transfer the boiler axis from the ground to ceiling girders top.

23.

Record the difference between the transferred boiler axis to center line of individual ceiling girder.

57

Fig. 28

58

PREPARATION FOR DRUM ERECTION 1.

Mark the drum axis from F3 – F F4, F1- G2, B1- B2, Beam D, Beam G, Beam B1 – B2 center line and arrive at combustor axis.

2.

The drum, Combustor And Back Pass boiler axes shall be punch marked over WB‟s and ceiling girders G1 (L & R, G2 (L & R), G3 (For boiler drum and pressure parts Erection reference).

3.

Erect, align and weld the drum suspension support beam on either side of boiler axis as per approved drawing.

4.

Carry out LPI on welds.

5.

Erect. Align and weld cat head structure (“A” frame) for the purpose of drum lifting arrangement as per contract drawing.

6.

Erect, align and weld staircase on both sides up to ceiling girder level an drum level (Ref. Section on Stairways & Galleries).

7.

Provide temporary approach ladder (from drum level to ceiling girder level) and platform for drum lifting operation.

8.

The minimum structural requirement are to be completed in all respect and the structure shall be cleared for drum Erection.

9.

The following are the minimum requirement of structure for drum erection. Product Group (PG) – 35 

Main, middle and auxiliary column



Horizontal beams between columns



Vertical bracings and tie member



Ceiling girders



WBs between ceiling girders



Ceiling bracings



Rolled beams required for drum lifting



Posts required for forming horizontal bracing at MBLs

59

PGMA

Description

Weight (Tons)

35-010

Foundation Material

9.7

35-110

Columns

591.0

35-120

Columns

877.0

35-130

Columns

317.0

35-190

Girder Pin Bearing

16.1

35-210

Ceiling – Combustor

134.3

35-220

Ceiling Combustor

8.6

35-230

Ceiling – Bracing

48.2

35-240

Ceiling- Back pass

210.4

35-250

Ceiling – Back pass

47.1

35-510

Column Bracing

418.0

35-520

Column Bracing

486.0

35-700

HSFC Bolts

14.7

35-530

Column Bracing

604.6

35-390

Misc Structure

64.0

Total weight

3846.7

Floor Grill

3.0

G. Total

3849.7

Required floor and stairs along with Floor grills for Drum lifting is planned to be released under PGMA 35-390. PRODUCT GROUP (PG 36) 

Horizontal bracings on all main brace levels (MBLs) between columns and Out side columns.

60



Inside combustor expecting rear pass and Inside back pass excepting front side up to drum path.



Horizontal bracings left out in the drum path are to be erected immediately after drum erection.

61

POST DRUM ERECTION CHECKS AND WORKS 1.0

In completion of drum erection the following activities are to be carried out immediately. 

Check the vertically of column wherever possible and cross refer to verticality readings taken after ceiling girder alignment.



The left out member in MBL for drum erection in the combustor and back pass region are to be erected.



Erect the support structure for silencer.



Position the silencer on support structure and arrest temporarily for safety reason.



Erect align and weld all rolled beams for starting of pressure part work.

2.0

Complete the erection alignment and welding of monitor roof assembly (Ref Fig No. 25A & 25B)

3.0

The balance members of PG 35 and 36 are to be erected aligned and welded in a phased manner for ease of pressure parts erection and approach to various locations.

4.0

Complete the erection, alignment and welding of PG 39 members (Fans and duct structure) in a phased manner as per site progress.

5.0

Complete the erection, alignment and welding of structure between units, boiler and „D‟ row columns.

6.0

Do not cut structural members due to interference of boiler components. Consult the designer for comments / correction work.

62

Fig. 29

63

PLATFORM, STAIRWAYS & GALLERIES Structures for stairways shall be erected such that the proper slope, as envisaged in the design – documentation are maintained. Stairway structural shall be checked up for proper fit up of Toe plates and end connections of step / treads. If due to some reason the connections are loose and the toe plates are not available they shall be re-fixed/ tightened again before commissioning. Stairs shall be guided by two sets of hand rails and posts and special bends. They shall be fitted parallel on each side of the stair stringer beams either through bolted connection or welded connection as per dimensions given in the design documentation. The spacing of the posts shall not be greater than 1800 mm or as specified in the design documentation. Hand railing between two levels shall be connected smoothly by using special bends or 90 elbows. Butt weld joints of tubes shall be grounded smooth so as to avoid human injury during usage. Hand railing and posts having well- finished and not got bent or twist during transporation, stacking and handling shall be used. They shall be fixed to the structural beams such that they are truly parallel or perpendicular to the member concerned. Bottom, stairway, after alignment of the complete stairway system‟s shall be properly anchored to the foundation with anchoring materials. Platform, beams around the main structures connected and stiffened to the main structure as per the design documentation. Level of platform/ gallery shall not vary ± 5 mm than actually required. Platform coverings such as floor gratings or chequered plated shall be fixed to the beams by welding or clipping as envisaged in the design. Wherever floor gratings are fixed using clips and studs, they shall be done using minimum of four clips per grill. Clips shall be fixed that they shall not project above the grating so as to cause hindrance to walkway. Load bearing bars of the grills shall always be kept such that they are perpendicular in its own plane to the main load bearing member of the platform beam. Platforms around the furnace shall be fitted with two sets of parallel hand railings and vertical handrail posts such that they are always available to give the safety requirements for walkway around the steam generator. They shall be fixed as per design documentation. All square corners shall be connected smoothly using 90 elbows. Any undue projection around the floor shall be offset by providing necessary hand railings. 64

Guard plates shall be fixed as per contract drawing so s to give the necessary safety facility during erection and usage. Horizontal bracings at platform levels and below platform s wherever envisaged shall be erected as per the design documentation etc., to give stability to the main structure. Unless or otherwise specified clear head room of 2000 mm shall be checked and ensured. Openings or cutouts in floor gratings caused due to equipment or pipe routing shall be finished smooth by proving edge strips or kerbs. Floor levels shall be marked or exhibited at important visible locations around the furnaces port ion and near stairway portions. Note: Ensure that undue excessive loadings are avoided on the platform than for which they are designed. Concentrated loads caused due to piling of welding gas cylinders shall be avoided.

65

Fig. 30

66

Fig. 31

67

Fig. 32

68

Fig. 33

69

Fig. 34

70

Fig. 35

71

Fig. 36

72

Fig. 37

73

Fig. 38

74

Fig. 39

75

STRUCTURAL STEEL ERECTION NOTES i)

Edge preparation for bevel welds to be made as per BPS: 519001: 700 unless otherwise stated.

ii)

Surface preparation holes is 12.5 Microns and edge preparations for welds is 25 Microns unless otherwise specified.

iii)

Tolerance on drilling and bolting of steel structures shall be according to BPS 528502: 7300.

iv)

Holes for bolts shall not be formed by gas cutting process.

v)

Column levels to be marked at every 5 meter level starting from the nearest whole number from top (if not done in shop).

vi)

No painting shall be done for a distance of 75 mm from a group of HSFG Bolts.

vii)

All field connections shall be either by bolting or by welding. HSFG bolts shall conform to B8 4395 Part – I and Black Hexagonal Bolts to IS: 1367.

viii)

Every bolt shall be provided with a steel washer under the nut so that no part of the threaded portion of the bolt is within the thickness of the parts bolted together.

ix)

Cement washing or any other treatment provided on the surface of structural materials near HGFG Bolt connected are to be removed by wire brushing before the structural members are fastened.

x)

Ends of members are to be cut at site to suit opposite profiles (if not already done).

xi)

Ends of the members are to be welded all round to opposite profiles are as follows, where ever not indicated otherwise. Sl. No.

Section

Size of Weld

1.

I 600, L130 X 130 X 12 L150 X 150 X 12

10

2.

I 500 L 450 X 1400 X (1400) L 100 X 100 X 10

8

3.

I 350, I 300, (300, [250, 1250]) L 80 X 80 X 8

6

4.

I 200, ([200],150, L75 X 75 X 61) L 65 X 65 X 6, L50 X 50 X6

4

5.

I 150, I 125

4

76

xii)

The symbol shown the floor drawings indicate the symbol shown direction of load bearing bars of the grill.

xiii)

If width of gap due to discontinuation of floors/ platforms exceeds 150mm, ends of such floors/ platforms shall be provided with hand railings.

xiv)

Place one hardened steel washer under element turned (nut or bolt head) during tightening.

xv)

HSFG Bolts once tightened are not to be slackened, removed and Reused.

xvi)

Hand railing shall not cantilever more than 900 mm beyond the last handrail post.

xvii)

Any partially erected or unstiffened portions of the structure are to be temporarily braced for wind and erection loads by using guys, false work, cribbing or whatever other means are determined to be necessary. Temporary‟ bracing is to remain in place until that portion of the structure has been bolted up and is self supporting. 

xviii)

Final tightening or welding of connections shall not be performed until that portion of the structure to be stiffened has made aligned and made plumb within the specified tolerances.

Flame cutting shall be permitted for coping, trimming, cutouts or other minor rework of members required to be performed with the approval of, or as directed by the Erection Engineer. Flame cutting is not permitted for relocating or enlarging of bolt holes.

77

MANPOWER REQUIREMENT FOR STRUCTURE ERECTION (UPTO DRUM ERECTION)

S.NO

CATEGORY

MANDAYS

1.

Fitters

1200

2.

Rigger/Khalasi

3600

3.

Welders

1350

4.

Tack Welders

1200

5.

Grinders

300

6.

Gas Cutters

600

7.

Electrician

300

8.

Helpers

3000

9.

Winch Operator

300

10.

Crane Operator

300

Total

12,150

78

Fig. 40

79

BOILER SUPPORTING STRUCTURE ERECTION TOLERANCES I. Foundations: Rough concrete boiler column pedestals top level:

-25 mm

Top level difference between Pedestals:

+ 15 mm 15 mm

Foundation bolt projection above nut:

± 15 mm

Grouting gap: 30 mm (Min.) 70mm (Max.) Dimension between individual column pedestal centres (adjacent) 1 mm per Metre Max. ± 5 mm Dimension from first row to last column pedestal

1 mm per Metre Max. ± 15 mm

Foundation bolt hole pitch difference

± 3 mm

Individual column pedestal diagonal difference

10 mm (Max.) 1 mm / Metre

Cumulative difference

25 mm (Max.) 1 mm / Metre

II.

Column

Individual column piece camber

1 mm / M (Max 10 mm)

Individual column piece sweep

1 mm / M (Max 10 mm)

Total length of the column after trial assembly ± 15 mm Camber for the total length of column

1 mm / M, (Max. 18 mm)

Sweep for the total length of column

1 mm / M (Max 18 mm)

Out of vertically of the column / structures

1 mm / M (Max 25 mm)

Elevation of column at reference level

± 5 mm

80

III. Ceiling Girders Root gap at the erection joint of the ceiling girders

For flange 4 to 6 mm For web 6 to 10 mm

Camber and sweep of the individual ceiling

1 mm / Metre,(max. 5 mm)

girder piece For assembled ceiling girders for sweep as

1mm/ Metre,(Max. 15 mm)

well as Camber Position of bottom bolt hole with reference to

± 3 mm

centre of the girder Mating surface of the bottom flange of the ceiling girder where it comes and sirs over the column top pieces shall not have twist or warpage more than 2 mm. Tolerance for intermediate girder spacing centre to centre

± 5 mm

Diagonal difference between two adjacent ceiling girders

25 mm Max.

Boiler axis transfer tolerance at ceiling girder level.

± 12 mm

IV.

GENERAL Tolerance on platform levels Straight flat bars of floor grills (load bearing members shall span in between two supporting beams of platforms). Other requirements shall be as per the drawing.

81

GROUTING I)

GROUTING OF COLUMN FOUNDAMTION

Grouting of any foundation is an important item of work, which merits careful attention, considering the role it plays in ensuring smooth functioning of the equipment. The term „Grout‟ refers to the materials for filling the gap between the base and the rough top surface of the foundation and for filling the Annular space in bolt holes. Column Base Grouting Stage The grouting of annular space the column bass shall be grouted after the completion of erection and alignment of first piece tier of all main and auxiliary column (bottom piece) with connected beams and vertical bearings. Under no circumstance, however, structural steel erection shall process beyond the First tier. Grounting Material Depending on the grout space to be filed the composition of the grout is varied. Thus for filling very small cavities and gaps mixture of ordinary Portland cement and water referred to as, Neat cement grout‟ is used. Where the hap is to be filled is more than 7mm, cement mortar‟ (i.e.) a mixture of ordinary Portland cement, and water is used. Where conditions permit it is Desirable to use, with the cement mortar, stone chips 6 mm and down graded. This mixture of cement mortar and stone chips is referred to commonly as „Cement concrete grout‟. The grout space below base plate shall be generally not less than 20 m or not more than 70 mm. Refer foundation drawing. Accordingly cement concrete grout is used for Boiler column Base Foundation Grouting. Preparation of the Grout 1. Proportions of grout shall b such as to produce a workable consistency. 2. The composition of the grout mix shall such that it ensures n ultimate strength equivalent to one grade higher than the grade of concrete adopted for foundation. E.g. If concrete foundation is MISO, Grout mix shall be M200. 3. The proportion of grout shall have minimum water required for giving consistency and, fluidity and to have minimum shrinkage. The extent of shrinkage will depend on the water content in the grout and keeping water minimum will control shrinkage.

82

Additives Apart from reducing water content, the shrinkage of grout could be controlled by using expansive additives. Aluminum power has been used for a long time as an additive to reduce shrinkage of grout. The theory relating to the use of aluminum powder is that it reacts with the alkaline constituents of cement and generates hydrogen gas, resulting in expansion of the mortar and thereby it enables the grout to fit snugly in the space which confines it. The proportion of aluminum powder additive usually recommended is – 1 teaspoonful (about 5 gm) for each 50kg of cement. The disadvantage of aluminum powder additives is that it is not pure, there may be delay in the chemical reaction while releasing hydrogen gas which may result in possible corrosion in the long run. There are some other patent admixtures for controlling the shrinkage or grout now available in the country. The details of two such patent admixtures of proven characteristics are given below (refer: Special Grouts). An acceptable plasticizer may be added to the grout mixer in a proposition recommended by the plasticizer manufacturer. All such grouts shall be thoroughly mixed and used immediately in 5 minutes. “Sand” for “ General Grouting” shall be graded within the following limits. Passing

2.36 mm sieve

95% to 100%

(IS 456)

Passing

1.18 mm sieve

65 % to 95%

(IS 456)

Passing

300 micron sieve

10% to 30%

(IS 456)

Passing

150 micron sieve

3% to 10%

(IS 456)

Cement concrete mix 1: 1: 1 (i.e.) one part of fresh Portland cement 1 part of well graded sand and 1 part of hand broken blue granite stone gelly passing through 6 mm can also be used for General Grouting. The Portland cement to be used shall conform to IS: 269 or equivalent. The recommended mortar content can be as below: Use

Mix – Proportion

Grout Thickness

Water / Cement Ratio

Fluid Mix

Under 25

1 Part Cement 1 part sand

0.44

General Grouting

25 mm and over but less than 50mm

1 part cement 2 Parts of sand

0.53

83

Special Grouts: a)

SHRINKOMP This is a ready mixed special cement and fine aggregate developed and marketed by M/S Associated Cement Co.Ltd., No sand or cement is to be mixed with this at site. It location permits, up to 20 kg of 6 to 10 mm size clean washed gravel may be added for each 50 Kg of Dry Shrinkomp. At present two varieties of shrinkomp are marketed by Mis associated Cement Co.Ltd., (viz) Shrinkomp-N and Shrinkomp-H. The N-Variety is readily available where as the H-Variety is only available of ordered in bulk quantities well in advance. The ultimate compressive strength of these varieties as guaranteed are as follows: Conbextra GP 1 Strength in Kg/Cm2

28 days - 450

Shrinkomp N (20)

Shrinkomp H (20)

7 Days – 140

340

28 days – 210

450

b. Ferrogrout This is an admixture produced by the Ferrosite Co. It has to be mixed with ordinary Portland cement and clean graded sand in prescribed proportions. The ultimate compressive strength of the Cement remains unaffected by adding this mixture. The mix proportion for the grout shall be one of the following alternatives. Add 20 kg of 6 to 10mm size stone chips (clean and graded) to 50 kg of „Shrinkomp – N‟ using 8 liters of water. In this proportion, mix enough grout for the space to be grouted. Batching of grout by fraction of a bag is not recommended. Or Add 50 kg of ordinary Portland cement with 100 ibs of Ferrogrout, 100 Ibs of clean dry sand 150 Ibs of stone chips 6 to 10mm size (clean and graded) using about 22.5 litres of water. In this proportion mix enough grout for the space to be grouted. Alternatively it is suggested for column grouting the usage of CONBEXTRA GPI or GP2 grouting mix (brand name) supplied by FOSROC Bangalore, which is also used for turbine foundation in place of important PAGEL grout mix. This has the following advantages. a)

More fluidity

b)

Non- Shrinkage

84

c)

Quick Setting

d)

High strength

Procedure The surface of the foundation to be grouted shall be thoroughly roughened and cleaned of al foreign matter such as grease, oil, dust, loose concrete chips etc. The space between the machine base and the top of foundation should be thoroughly cleaned with compressed air and moistened with water before applying grout. Oil or grease should be treated with a caustic solution and thoroughly flushed or removed by chipping to a sufficient depth. The machine base or sole plate should be cleaned of rust, mill scale, paint or oil. Water particles entrapped in the grout space shall be removed before grouting is started. Use proper form work on all sides of the base plate to prevent escape of the grout. Form work around the base plated shall be form to prevent any leakage of grout material. Mixing of the grout shall be one in a mechanical mixer for about 3 minutes to obtain a fluid of uniform consistency. It is desirable to mix the dry constituents thoroughly before adding water. The quantity of water may be varied slightly. At the discretion of Engineer – in- charge to suit each application. Mixing shall be done as close as possible to the area of application. Mixing shall be done as close as possible to the area of application. Place the grout uniformly and compact by thorough manual Roding except where insertion of needle vibrator is possible. The entire process of mixing, placing and compactness shall be done in a fast and continuous manner and grout shall be a single cast. Care shall be taken to see that grouting material is evenly spread under the base plate and the top rough concrete and uniform consistency is maintained. Curing should be done for a minimum period of 7 days. The exposed faces of grout may be covered with wet sack during the curing period. During this period it would not be advisable to load the foundation through substantial loads from columns.

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ANNEXURE – 5 HSFG BOLT TIGHTENING TIGHTENING PROCEDURE FOR HSFG BOLTS BY PART TURN METHOD 1.

Clean the HSFG bolting area. At the time of surface in contract should be free from paint or any other foreign material like oil, dust, burrs and other defects which would interfere with the development of friction between them.

2.

Ensure that the alignment of members is such that the bolts for the holes freely – forcing the bolts into the holes by means of hammering which will damage the threads, should be avoided at all costs.

3.

Fix all the ASFG bolts nuts (of specified length and grade) with correct washers.

4.

The bolted parts are to be in contact over the entire surface.

5.

The nuts shall be so placed in the joint that its identification mark is clearly visible after tightening.

6.

Hand tightens all nuts.

7.

Snug tighten all the bolts sequentially from fixed end to free end and inner to outer.

a)

If required, because of bolt entering and wrench operation clearance, tightening may be done by turning the bolt, while the nut is prevented from rotating.

b)

During tightening, the bolt head or nut should be held by hand spanner of spud wrench to prevent it from turning.

Snug tight Snug tight is tightening of bolt with correct size hand spanner by the single person, without nay leverage and additional force. This may develop a tension of approximately 5000 to 10000 ibs. It is good practice to take second run over the bolts with correct size hand spanner (by the same person without leverage) in the same sequence as above, to check the snug tight position. 8)

Make permanent location mark on each nut and the protruding end of the bolt as shown in Fig .1, to record their relative position. This mark may be made with paint or by using a cold chisel.

9)

Complete tightening of installed bolts by turning each nut to the specified angle with respect to the length of the bolt. Tolerance ± 30o (1 ½ of a turn)

86

This can be verified by the marking done on the bolt top and nut. 10)

Mark on one face of the nut to indicate the completion of tightening as shown in Fig: 2.

Note: Recheck for ensuring full tightening, which can be done by using calibrated torque wrench and bolt tension calibrator – min. 10% of bolts or 2 Nos. in each joint which ever is more. 

Use torque tightening chart obtained from Bolt Manufacturer

87

Fig. 41

88

ANNEXURE - 6 APPLICABLE PGMA WITH SUGGESTED ERECTION SEQUENCE Stage Description

Applicable PGMA

I. Foundation S1 to S22 Foundation Materials

35 -010

II. Columns, Horizontal Beams, Bracings First Tier (three sub- stages Erection (each sub0stage not exceeding 3 meters preferably at erection joints) 1st set of pieces 1.

S1 – S2 – S7 – S8 – Left side columns and Connected beams

2.

S3- S4- S9 – S13 – Left side columns and Connected beams

3.

S5 – S6 – S9 –S13 Left side columns and connected beams

4.

Stairways and landing platforms (Left Side)

(35-390, 36 -820)

5.

Repeat steps 1, 2 and 3 on the right side columns with connected beams

(35-110, 35-120 35-130)

6.

Connecting beams between steps 1 to 2 And 2 to 3

(35-510)

7.

Column S13 and Front Bracing S1L, S7L, S13, S7R, S1R

(35- 520)

8.

Side Bracing S7 to S12, left and right side

(35- 530)

9.

Stairs landing and hand railing and platforms (right side)

(35-390, 35- 820 35-850)

(35-110, 35 – 120 35-130)

iii to iv Columns, Horizontal Beams, Bracings Second - Tier (two sub- stages) Erection (each sub= stage as above)

v)

Repeated step 1 to 9 of first stage as above for second tier erection up to the ceiling bottom including stairways, platforms, galleries, hand railing etc.)

Repeat Above PGMAs

Girder Pin Connection Girders and welded beams Ceiling rolled beams Ceiling bracings

35-190 35-210, 35-240, 35-220, 35-250 35-230

89

vi)

Airheater and Second Pass Structure 

Column S50, S21 connecting beams

35-110 35-120 35-130



Rear bracings S7L, S15L, S21, S15R, S7R

35- 510 35- 520 35-530



Ceiling Girder

35-240 35-250 35-230



Ceiling Rolled Beam, welded beam Ceiling bracings

vii)

35-510

ROOF STRUCTURE (After drum lifting and major pressure part erection)

viii)



Roof structure over boiler



Structure for weather protection over burner floor 35-610



Structure for weather protection over drum floor

INTER – CONNECTING WALKWAYS (BETTER BOILERS) 

Foundation Materials



Elevation structure bracings

PGMA in



Interconnecting platform between boilers Interconnecting platform - Boiler and Main Building

PG 38



Floor grills, guard plates, hand rails



Elevator cladding sheets

90

APPLICABLE PGMA WITH SUGGESTED ERECTION SEQUENCE SUPPORTING STRUCTURE FOR ID SYSTEM Stage Description

Applicable PGMA

I.

Foundation Materials Bolts, Anchor channels

39-010

II.

Columns for Electrostatic precipitator Beams and bracing for Electrostatic precipitator

39-120

Duct supports between boiler an electrostatic precipitator

39-300

Duct supports between ID and chimney columns neared fans

39-140

iii.

lv.

39-150

39-300 Platforms floor grills and guard plate hand rails

39-810 39-850

V.

Stairways and ladders

39-820

vi.

Platform for Fan Hood for Motor

vii.

Fan handling structure

39-303

viii.

Pulley clocks for motor and fan handling

39-901

91

39-301 39-302

APPLICABLE PGMA WITH SUGGESTED ERECTION SEQUENCE APPLICABLE PGMA’S FOR STAIRWAYS AND GALLERIES



36-210

36-300

36-810

36-220

36-310

36-820

36-230

36-380

36-850

36-240

36-390

Materials:

Indian Standard rolled beam, channel,

IS 226, IS 2062, IS 1161

angle cleat sections etc.,

IS 1367.



Size of hand railings and posts.

Dia 34.2 x 3.25mm sphere Dia 70mm (wherever applicable).

92

Fig. 42

93

Fig. 43

94

FQA LOG SHEETS LIST SL.No

Description

Reference No.

1

Quality certification of civil foundation and top elevation of foundation

FQA – 01 – 3S – 00 –L -01

2

Boiler column spacing

FQA – 01-3S-00-L-02

3

Diagonal check between column pedestal

FQA – 01- 3S-00-L-03

4

Pitch distance of foundation bolts and diagonals

FQA – 01- 3S-11-L-04

5

Trial assembly of column piece camber and sweep of column piece and column measurement (without pre assembly)

FQA – 01- 3S-00-L-05

6

Ceiling girder pre assembly

FQA -01- 3S - 00-L-06

7

First tier column alignment

FQA -01- 3S - 00-L-07

8

Grouting gap

FQA -01- 3S - 00-L-08

9

Vertically of Boiler column

FQA -01- 3S - 00-L-09

10

Protocol on work completion for tier by tier erection

FQA -01- 3S - 00-L-10

11

Ceiling girder alignment

FQA -01- 3S - 00-L-11

12

Joint inspection protocol for completion of structure prior to drum erection

FQA -01- 3S - 00-L-12

95

REFERENCE DOCUMENTS SL.NO

Description

Reference No.

1

Boiler supporting structure

Pub. 2301

BHEL (T)

2

Tightening procedure of HSFG Bolts

Pub. 2302

BHEL (T)

3

Product check list for Boiler structure

BR (STR) – 200 /21)

FQA

4

Welding Manual Vol.I

WM (Com)

FQA

5

Welding Manual Vol II

WM (NDE) – Com

FQA

6

Field heat treatment schedule

HT – Com

FQA

7

FQA system Manual

PS – QASM

FQA

8

Handling equipment

O & M Manual

Stairways and Galleries

9

Issued By

BHEL (T)

a) Method of fixing handrail posts to platform beam b) Elbows c) Special bends

96